The invention relates to a seat of a vehicle, in particular, to an air lumbar support which utilizes an air bag and an electronic control circuit which controls the pressure of the air bag in response to an electrical coded command.
A driver driving a vehicle normally operates a steering wheel, an accelerator and a brake pedal, a transmission and switches in suitable manners depending on the road condition, the weather and road marks. It will be noted that these members have their operating end fixed in position. By contrast, the physical features of drivers vary from driver to driver. Consequently, a lumbar support used in the prior art is usually adapted to have the resilience of the lumbar spring adjusted through a lever operation. In another lumbar support, air is pumped into an air bag through a manual pump or discharged therefrom through a manual release valve. As will be appreciated, a manual adjustment is cumbersome in any event. Pending U.S. patent application Ser. No. 235,173, filed Feb. 17, 1981, U.S. Pat. No. 4,404,632 discloses a seat back in which a motor is mounted to establish and adjust the resilience of a lumbar spring. However, a mechanism used to adjust the resilience of the lumbar spring is complex in construction, requiring a complex positioning control because of the need to use an encoder and a position sensor.